While, a scalpel, is used for the purpose of incising a tissue of a living body, an electric scalpel or laser scalpel is a surgical instrument which has the function of simultaneously cauterizing tissues and cauterizing blood vessels such as capillary vessels and thereby simultaneously effecting the incision and hemostasis and which is suitable for use in the field of operations in which both the incision and hemostasis are effected. However, since these surgical instruments simultaneously effect the incision of a tissue and the cutting of blood vessels or nerves, in the case of an operation on such an affected part as a liver or brain tissue where a large number of blood vessels or nerves gather or in the case of an operation on any other affected part to be operated on where it is desirable to leave the blood vessels or nerves as such, it is rather difficult to use an electric scalpel or laser scalpel and thus a recourse is had to a scalpel made of steel or the like which has heretofore been in use.
As regards the conventional surgical instruments utilizing the tissue cutting or shattering capacity of ultrasonic vibrations, the ultrasonic surgical instruments which have been put in practical applications include those which chip bones or joints in the fields of plastic surgery and general surgery, surgical instruments for operating on cataract in the field of ophthalmology and dental instruments for removing the tartar on teeth. However, these surgical instruments utilizing ultrasonic vibrations are not designed to display ultrasonic vibrations of an amplitude and power only sufficient to extensively shatter tissues and they are each used as an exclusive surgical instrument for an extremely limited surgical field.
On the other hand, Japanese Patent Laid-Open Publication No 54-152383 (1979) discloses an ultrasonic surgical instrument having a magnetostriction type transducer composed of a laminate of nickel alloys having different mechanical characteristics and intended for application to a wide range of body tissues.
However, in the case of a magnetostriction type transducer using ferrite, for example, the transducer is strong to axial compression but weak to axial elongation and therefore the amplitude cannot be increased. Also, in the case of a nickel type magnetostriction transducer the transducer lacks in shock resistance so that the transducer tends to be damaged if a large load is applied to the forward end of the horn and also the mechanical Q inevitably becomes low as compared with the electrostriction type transducer, thus increasing the electric loss, correspondingly increasing the heat generation of the transducer and giving rise to the possibility of damaging the transducer unless the thus generated heat is removed by cooling means such as water.
Also, a known ultrasonic oscillation device employing an electrostriction type transducer is disadvantageous in that any attempt to increase the amplitude of the horn forward end causes a difference between the phase of an output power waveform for the vibration of the ultrasonic transducer and the phase of a feedback voltage waveform, thus making it impossible to increase the amplitude.